Freely Scalable Quantum Technologies using Cells of 5-to-50 Qubits with Very Lossy and Noisy Photonic Links

TL;DR

This paper demonstrates that quantum computing with small, scalable qubit cells interconnected by lossy, noisy photonic links is feasible using loss-tolerant entanglement purification and surface code protocols, achieving practical clock speeds.

Contribution

It introduces a scalable quantum architecture utilizing cells of 5-50 qubits connected via lossy links, enabling feasible quantum computing despite high photon loss.

Findings

Entanglement purification tolerates 98% photon loss.

Surface code protocol achieves 13.3% network noise threshold.

Kilohertz clock speeds are possible with current local gate fidelities.

Abstract

Exquisite quantum control has now been achieved in small ion traps, in nitrogen-vacancy centres and in superconducting qubit clusters. We can regard such a system as a universal cell with diverse technological uses from communication to large-scale computing, provided that the cell is able to network with others and overcome any noise in the interlinks. Here we show that loss-tolerant entanglement purification makes quantum computing feasible with the noisy and lossy links that are realistic today: With a modestly complex cell design, and using a surface code protocol with a network noise threshold of 13.3%, we find that interlinks which attempt entanglement at a rate of 2MHz but suffer 98% photon loss can result in kilohertz computer clock speeds (i.e. rate of high fidelity stabilizer measurements). Improved links would dramatically increase the clock speed. Our simulations employed local gates of a fidelity already achieved in ion trap devices.